Telephone system.



No. 888,870. PATENTED MAY 26, 1908. E. R. GORWIN. TELEPHONE SYSTEM.

APPLICATION FILED MAY 11, 1906.

' a) '0 t (u 'r 1 I a o e r o 3 i 1" f PkIIIHIII' g A TTORNE Y ITNESSES. I INVENTOR ER. CORWIN ELMER R. CORWIN, OF CLYDE, ILLIN IINIT STATES ATENT OFFICE.

COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented May 26, 1908.

Application filed May 11, 1906. Serial No. 316,358.

T 0 all whom itmay concern:

Be it known that I, ELMER R. CORWIN, citizen of the United States, residing at Clyde, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone Systems,

of which the following is a full, clear, con- 1 operate with the plugs of the cord circuits and the jacks in which the plugs are to be inserted to effect the desired control of the supervisory signals, talking strands of the link circuits being employed for this purpose, as are also preferably talking portions of the circuits extraneous to the link circuits.

Where my invention is employed in the circuits used in inter-connecting subscribers, the extraneous means taking part in the control of the supervisory signals (which may be one or more to a link or cord circuit, as desired) desirably resides in the line relays that are also used for effecting calling signals at the exchange. \Vhere cut-off relays are employed to efl'ace the line signals, these outoff relays, in accordance with another feature of my invention, are adapted for inclusion in the same circuits with the supervisory signals. The cut-oif relay and supervisory signal circuits are local, and in order that the government of the line relays and the government of the cut-off relays may be totally distinct, I provide one battery for the cut-off relay and supervisory circuits and another battery for the line circuits, which latter battery may also serve to supply battery current to the transmitters at the sub-stations. As is' well known, the common batteries employed in common battery systems have one pole grounded for circuit protection, and, as my invention is of particular service in connection with multiple switchboard prac tice, I prevent the occurrence of false signals and improper busy tests by providing one battery for talking purposes and another battery for the supervisory signaling and cut-ofi The line relays are desirably included in bridge of the telephone lines and in series with the common battery, and in order that the functions of the line relays, on the one hand, and the cut-off relays and the supervisory signals, on the other hand, may perform without interference, I include condensers in the talking circuits between each cut-off relay and the associate line relay, which condensers are desirably permanently included in the lines, whereby a two sided system may be produced that will permit of conversation and portion of the talking circuit to enable the functioning of the signaling and cut-off relays, whereby the provision of third conductors for the cord circuits and third parts for the jacks may be dispensed with, though I do not wish to be limited in all embodiments of my invention to these characteristics.

I will explain my invention more fully by reference to the accompanying drawing, and will point out other advantages thereof in connection with the drawing, in which Figure 1 illustrates the invention as applied to telephone exchange systems including subscribers lines. Fig. 2 is a schematic view more briefly outlining the circuits that are shown in Fig. 1.

Like parts are indicated by similar characters of reference in both figures.

There are indicated two of many substations, A, B, each in the embodiment of the invention shown having a transmitter 1, a receiver 2, a call bell-3, a switch-hook 4, a condenser 5, and an impedance coil 6, together with suitable contacts and circuit connections, whereby when the telephone receivers 2 are upon the switch-hooks, the bells 3, together with the condensers 5, are bridged across the sides of the telephone lines 7, 8, and whereby when the telephone receivers are removed from their hooks, the

relay devices.

also permit of the use of a.

018, ASSIGNOR TO MONARCH TELEPHONE MANUFACTURING bridges including said signaling bells are and 8 of the telephone lines are, in multiple switch-board practice,'multiplied to sleeve contact springs 9 and tip contact springs 10, respectively, of multiple spring jacks, though the invention may be useful in connection with switchboards that are not multiple switchboards, in which case but one spring jack need be supplied to a line. In multiple switch-board practice, one of the acks may act as an answering jack, the answering jacks, as is understood, being suitably distributed among the different sections of the switch-board, the multiple jacks being multiplied to the several sections of the switchboard, which grouping arrangement, or any other preferred grouping, is well understood.

In the embodiment of the invention shown, the line relays 11 have their windings desirably permanently associated with the corresponding telephone lines and the common talking battery 12, the circuit of this talking battery being desirably normally closed at each cut-ofl' relay switch 13, so that when a subscriber removes his telephone, the line relay 11 may become energized, whereby circuit through the line signal 14 of the calling subscriber may become closed by way of a companion cut-oil relay switch 15 and the line relay contacts 16, 17, the circuit of the line signal 14 desirably, though not necessarily, including the battery 18 distinct from the battery 12. It is not as important to provide a special battery 18 for the line signals as it is to provide said battery for the supervisory signals and cut-oil relays, as will appear.

In the embodiment of the invention shown, there may be a number of cord or link circuits, one being illustrated, each including an answering plug 19 and a connecting plug 20, the tips of the plugs being united by a tip strand 21 while the sleeves of the plugs are united by a sleeve strand 22, condensers 23, 24 being included in the strands of the cord circuits where double supervision is desired. When the battery 12 is employed for the purpose of supplying the transmitters at the substations with current, which em ployment does not need to begin until they cord circuit is connected with a calling line, I desirably connect one pole, the grounded pole as shown, with a subscribers line or lines by way of the conductor 25 that has connection between the impedance coils 26, between which the condenser 23 is interposed, the battery 12, assuming now a complete connection between subscribers, supplying current to the substation A from its grounded pole through impedance 26, the tip of the inserted. answering plug 19, the tip spring of the jack belonging to subscriber A,

the limb 8 of said subscribers line, through the transmitter 1, the impedance coil 6, the winding of line relay 1]., back to the ungrounded pole of the battery 12. A similar circuit is established through similar parts of the connecting plug for supplying current to the substation B and the line relay 11 corresponding to said substation. When the plugs are inserted into the jacks of connected subscribers, local circuits are established for the-cut-ofl relays 27, each circuit including a common signaling battery 18, a common impedance device 28, the sleeve contacts of the engaging plugs and jacks, the winding of the cut-off relay 27, the contacts 16 and 29 of the corresponding line relay 11, the resistance 30, back to the remaining pole of the battery 18. l/Vhile the grounded terminal of the battery 12 is now connected with one side of each line by way of the tip strand of the link circuit and is disconnected from the lines at 13, yet the said battery remains efiecti ve for further signaling purposes by reason of its continued connection through the line relays 11, which line relays are energized as long as the subscribers have their telephone receivers off their hooks.

It is understood that when a subscriber initiates a call the conditions are such that circuit is closed through the corresponding line signal 14 by reason of the engagement of the parts 16, 17 of the line relay, and that when theoperator inserts the answering plug, the cut-off relay 27 of the corresponding calling line is energized to open the circuit of the 0perated lam 14 at 15, the cut-oil relays thereby desirably effacing the signals by opening the circuits of signaling devices, though I do not wish to be limited to this way of eiiacing calling signals. It will be seen that the effacement of the calling signals may be effected without interfering with the circuits of the relays that cause these signals, whereby these relays, the line relays 11, may be used to enable the subscribers to effect partial control over the supervisory signals, preferably lamps 31, 32, though I do not wish to be limited to the. use of the same relays 11 for enabling the subscribers partially to control the su ervisory signals and the line signals. It wil be seen that the su ervisory signals 31 32 are included in locaF circuits containing the cut-off relays, one lamp to a circuit.

During the time the receivers 2 are off their hooks, the line relays 11 are energized and the corresponding supervisory signal is included in circuit with the corresponding cutoft relay 27, the corresponding contacts 16 and 29 and the registering contacts of the corresponding ack and the plug inserted therein, and as the re1ay'27 is of high resistance, say 600 ohms when a 20 volt battery 18 is employed, the corresponding supervisory or disconnect signal lamp fails to glow until the connection is broken at 16 and 29 and the armature 16 rests against its normal contact upon the denergization of the corresponding line relay 11 (this operation occurring when the corresponding subscriber restores his telephone upon its switch-hook), whereby the resistance 30, say of 25 ohms, is substituted for the resistance of the cut-off relay 27, permitting the corresponding supervisory signal to glow. The cut-off relays 27 are permanently associated with the subscribers lines, but, in order that their action may be entirely local, a condenser 33 is associated with each line and affords a path that is continuous to voice currents, but affords conductive separation between the circuits of the corresponding line relay and the corresponding cut-off relay.

It will be seen that each subscriber by restoring his telephone, causes what constitutes a closure of a supervisory lighting circuit at one point, this lighting circuit having previously been closed at another point by the corresponding jack and the inserted plug, this supervisory lighting circuit being broken at this jack of the operator when she withdraws the plug therefrom.

Inasmuch as there are illustrated two supervisory signals 31, 32, and, in order that no extra cord strand need be su plied, I interpose a condenser 24 between the supervisory signals that afford the-necessary separation of these signals electrically, while permitting a'continuity of the talking circuit.

I have not described the functions and circuits of the operators listening key 34 and ringing key 35, as the use of these agencies and associate parts is sufficiently well understood by those skilled in the art.

It will be seen that the supervisory signal circuits, in the embodiment of the invention shown, include each a talking contact (as 9) of a jack and the talking contact (as the sleeve contact) of a plug.

The test circuit is clearly illustrated, the busy condition of the line being manifested by a click in the operators receiver. If an operator with a connecting plug, tests a line that is already busy, the test circuit is established from the upper pole of battery 18, through the impedance device 28, the called subscribers supervisory signal lamp 32 the sleeve of the plug already inserted into a jack of the busy line at another section of the switch-board, the testing thimble of the jack being tested, the tip ofthe connecting plug that is performing the test, the operators receiver 36, the impedance test coil 38, the operators listening key being actuated, back to the lower pole of the battery 18, this being the circuit that is established when a plug has previously been inserted at another section of the switch into the jack of a calling subscriber. Prior to the insertion of a plug into the jack of a calling subscriber, and owing to the removal of the calling sub scribers telephone from its switchhook, the lower terminal of battery 18, the calling subscribers ack thimbles are made busy, for it will be seen that the upper pole of the battery 18 is connected with these test thimbles by way of the line lamp 14 and the cut-off relay 27, this connection existing, of course, only until the operator responds.

WVhile I have indicated metallic circuit lines, I do not wish to be limited to the same.

I have herein shown a telephone exchange system in which the cord circuits are each provided with two plugs and I have shown spring plugs. It is obvious, however, that characteristics of my invention are applicable to other types oftelephone exchange systems, and I do not, therefore, wish to be limited to those systems in which link circuits having two manually operated plugs are employed. While I have shown spring jacks for the telephone lines, I do not wish to be limited in all embodiments of the invention to such types of connecting switches.

It will be seen that I have )rovided a telephone exchange system including metallic telephone lines extending to an exchange where double talking conductor cord circuits are employed and where supervisory or disconnect signal circuits are employed that are local to the exchange. These are important features of the system herein shown and forming the subject matter of certain of the claims.

It will be seen that by the system illus* trated I am enabled to accomplish all of the results hitherto outlined, and while I prefer the embodiment of the invention specifically set forth and illustrated, I do not wish to be limited to the precise instrumentalities shown, as modifications may be made without departing from the spirit of my invention, but,

Having thus described my invention, I claim as new and desire to secure by Letters Patent the following 1. In a multiple switch-board system, the combination with metallic telephone lines each terminating at the exchange in a plurality of jacks or connecting switches, a double talking conductor cord circuit for connection with the jacks, a disconnect signal, a circuit therefor local to the exchange including a portion of a talking conductor of the cord circuit, registering contacts of a jack or switch and the plug or switch of the cord circuit engaging said jack, a line signalefi'ecting relay in association with the telephone line acting in combination with the said plug and jack to govern the operation of the disconnect signal, apparatus at the stations of the tele hone lines governing the operation'of the ine relays, a cut-off relay for effacing the line signal included in the same circuit with the disconnect signal, said line relay effecting the operation of said line signal when a call is initiated over said telephone line, one battery or source of current for supplying the line relays of said telephone lines and the transmitters at the subscribers stations of said lines, another battery disjacks for receiving the answering tinct from the aforesaid battery adapted to be included in the disconnect signal circuit, a test circuit including said latter battery, a sleeve contact of an inserted plug, the thimble of the jack receiving said plug, the test contact of the connecting plug, the dis connect signal, and a testing device in circuit with said test contact.

2. In a multiple switch-board system, the combination with metallic telephone lines each terminating at the exchange in a plurality of jacks or connecting switches, a double talking conductor cord circuit for connection with the acks, a disconnect signal, a circuit therefor local to the exchange including a portion of a talking conductor of the cord circuit, registering contacts of a jack or switch and the plug or switch of the cord circuit engaging said jack, a line signaleffecting relay in association with-the telephone line acting in combination with the said plug and jack to govern the operation of the disconnect signal, apparatus .at the stations of the telephone lines governing the operation of the line relays, the circuit of the disconnect signal also including a portion of a talking conductor of the tele hone'lines, a cut-ofi relay for effacing' the line signal included in the same circuit with the disconnect signal, said line relay effecting the operation of said line signal when a call is initiated over said telephone line, one battery or source of current for supplying the line relays of said telephone lines and the transmitters at the subscribers stations of said lines, another battery distinct from the aforesaid. battery adapted to be included in the disconnect signal circuit, a test circuit including said latter battery, a sleeve con tact of an inserted plug, the thimble of the jack receiving said plug, the test contact of the connecting plug, the disconnect signal,

and a testing device in circuit with said test contact. I

3. In a multiple switch-board system, the combination with metallic telephone lines each terminating at the exchange in a plurality of jacks or connecting switches, a double talking conductor cord circuit for connection with the jacks, a disconnect signal, a circuit therefor local to the exchange including a portion of a talking conductor of the cord circuit, registering talking contacts of a jack or switch and the plug or switch of the cord circuit engaging said jack, a line signal-effecting relay in association with the telephone line acting in combination with the said plug and jack to govern the operation of the disconnect signal, apparatus at the stations of the telephone lines governing the operation of the line relays, a cut-off relay for effacing the line signal included in the same circuit with the disconnect signal,

- said line relay effecting the operation of said line signal when a call is initiated over said telephone line, one battery or source of current for supplying the line relays of said telephone lines and the transmitters at the subscribers stations of said lines, another battery distinct from the aforesaid battery adapted to be included in the disconnect signal circuit, a test circuit including said latter battery, a sleeve contact of an inserted plug, the thimble of the jack receiving said plug, the test contact of the connecting plug, the disconnect signal, and a testing device in circuit with said test contact.

4. In a multiple switch-board system, the combination with metallic telephone lines each terminating at the exchange in a plurality of jacks or connecting switches, a

.double talking conductor cord circuit for connection with the jacks, a disconnect signal, a circuit therefor local to the exchange.

including a portion of a talking conductor of the cord circuit, registering contacts of a jack or switch and the plug or switch of the cord circuit engaging said jack, a line signal effecting relay in association with the telephone line acting in combination with the said plug and jack to govern the operation of the disconnect signal, apparatus at the stations of the telephone lines governing the operation of the line relays, a cut-off relay for elfacing the line. signal included in the same circuit with the disconnect signal, said line relay effecting the operation of said line signal when a call is initiated over said telephone line, one battery or source of current for supplying the line relays of said telephone lines and the transmitters at the subscribers stations of said lines, another battery distinct from the aforesaid battery adapted to be included in the disconnect signal circuit,

a test circuit including said latter battery, a sleeve contact of an inserted plug, the thimble of the jack receiving said plug, the test contact of the connecting plug, and a testing device in said circuit with said test contact.

5. In a multiple switch-board system, the combination with metallic telephone lines each terminating at the exchange in a plurality of jacks or connecting switches,a double talking conductor cord circuit for connection with the jacks, a disconnect signal, a circuit therefor local to the exchange including a portion of a talking conductor of the cord circuit,

registering contacts of a jack or switch and the plu or switch of the cord circuit engaging said jack, a line signal-effecting relay in association with the telephone line acting in combination with the said plug and jack to govern the operation of the disconnect signal, apparatus at the stations of the telephone lines governing the operation of the line relays, the circuit of the disconnect signal also including a portion of a talking conductor of the telephone lines, a cut-off relay for effacing the line signal included in the same circuit with the disconnect signal, said ssss'rc line relay effecting the operation of said line signal when a call is initiated over said telephone line, one battery or source of current for supplying the line relays of said telephone lines and the transmitters at the subscribers stations of said lines, another battery distinct from the aforesaid battery adapted to be included in the disconnect signal circuit, a test circuit including said latter battery, a sleeve contact of an inserted plug, the thimble of the jack receiving said plug, the test contact of the connecting plug, and a testing device in circuit with said test contact.

6. In a multiple switch-board system, the.

combination with metallic telephone lines each terminating at the exchange in a plurality of jacks or connectin switches, a double talking conductor cor circuit for connection with the jacks, a disconnect signal, a circuit therefor local to the exchange including a portion of a talking conductor of the cord circuit, registering talking contacts of a jack or switch and the plug or switch of the cord circuit engaging said jack, a line signaleffecting relay in association with the telephone line acting in combination with the said plug and jack to govern the operation of the disconnect signal, apparatus at the stations of the telephone lines governing the operation of the line relays, a cut-off relay for effacing the line. signal included in the same circuit with the disconnect signal, said line relay effecting the operation of said line signal'when a call is initiated over said telephone line, one battery or source of current for supplying the line relays of said telephone lines and the transmitters at the subscribers stations of said lines, another battery dis tinct from the aforesaid battery adapted to be included in the disconnect signal circuit, a test circuit including said latter battery, a sleeve contact of an inserted plug, the thimble of the jack receiving said plug, the test contact of the connecting plug, and a testing device in circuit with said test contact.

In testimony whereof, I hereunto subscribe my name this 27th day of April A. D.

ELMER R. CORWIN. Witnesses:

, G. L. 'ORAGG,

LEON SrRoH. 

